/Engine/Source/Runtime/Core/Public/GenericPlatform/GenericPlatformMisc.h
Show a message box if possible, otherwise print a message and return the default
Very strange convention...not really EAppReturnType, see implementation
static [EAppReturnType::Type](API\Runtime\Core\GenericPlatform\EAppReturnType__Type) MessageBoxExt ( [EAppMsgType::Type](API\Runtime\Core\GenericPlatform\EAppMsgType__Type) MsgType, const TCHAR * Text, const TCHAR * Caption )